Fans are commonly just tagged onto the lighting circuit with no protection, but for a couple years now fusing has been strongly encouraged to comply with manufacturer instructions, much the same way previously with showers and RCDs.

How can you compare fusing both lives with fusing a neutral JP? That's just stupid! How to you see three phase boards and sw-fuses?

Its fine running the fan off the lighting circuit as long as the mcb is 6 Amps and lets face facts this is standard practice. Hover sometimes inrush probs due to florries etc are overcome by the fitting of a 10 Amp mcb in place of the 6 amper - this effectively negates the fan guarantee, and can cause the fan to go into ''Catherine Wheel Mode''..

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No JP, the problem is that IF the fan manufacturer stipulates that a 3 amp fuse should be incorporated in the supply that's what should be done. Our regs. state that manufacturers instructions must be followed. Imagine what would happen in the case of a fire for instance, investigators find that no fuse was provided so the installer could be held responsible! (very unlikely of course but I wouldn't want to risk it)

Morning,
So to surmise (to get clear in my own head!): take a feed from the bathroom lighting to an FCU. Feed that to a triple pole isolator and feed the fan with that. Place the FCU and TP isolator next to one another on the outside above the bathroom door.

Its fine running the fan off the lighting circuit as long as the mcb is 6 Amps and lets face facts this is standard practice. Hover sometimes inrush probs due to florries etc are overcome by the fitting of a 10 Amp mcb in place of the 6 amper - this effectively negates the fan guarantee, and can cause the fan to go into ''Catherine Wheel Mode''..

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Regardless of whether a 6A or 10A BS EN 60898 circuit breaker is used or a 5A BS 3036 or BS 1361 / BS 88-3 fuse, or a 3A BS 1362 fuse none of these will provide any protection to the fan. The point is simply about adherence to manufacturers' instructions. But the sensible way to achieve 3A fuse protection is to fit an FCU with a 3A fuse in it, and supply the bathroom light from it, and then take the fan off the bathroom light. Then both permanent line and switched line are pointlessly fused.

Regardless of whether a 6A or 10A BS EN 60898 circuit breaker is used or a 5A BS 3036 or BS 1361 / BS 88-3 fuse, or a 3A BS 1362 fuse none of these will provide any protection to the fan. The point is simply about adherence to manufacturers' instructions. But the sensible way to achieve 3A fuse protection is to fit an FCU with a 3A fuse in it, and supply the bathroom light from it, and then take the fan off the bathroom light. Then both permanent line and switched line are pointlessly fused.

Morning,
So to surmise (to get clear in my own head!): take a feed from the bathroom lighting to an FCU. Feed that to a triple pole isolator and feed the fan with that. Place the FCU and TP isolator next to one another on the outside above the bathroom door.

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Tbh the FCU could be anywhere, but IMHO the isolator should be easily accessible for local and easy isolation, just my take though.

Thanks guys. I will check up on what fusing is required by my Manrose inline fan - if it does say 3 Amps then I will knock my dedicated supply to bathroom down to 3 Amps - I can put an FCU below my DB (not yet fitted) - all good stuff lads tbqh.

I think the 3A fuse might just about discriminate with a 6A mcb, if the overload generated by a stuck rotor is pulling overload current. The 3A is more likely to blow and release the load than the 6A. I expect a stuck fan due to the blades jamming is going to get hot and potentially busrst in to flames. Whether this has any substance, I don't know, just my own thoughts. 3A could probably suffer 6A for a short time whereas a 6A would probably hold up to 10A?

In a sheltered housing scheme we do maintenance on, a fan in a bathroom ceiling caught fire (well, smoked the loft out). Since then, the estates manager has instructed yearly cleaning to be done, and MWC issued for each fan cleaned!

In a sheltered housing scheme we do maintenance on, a fan in a bathroom ceiling caught fire (well, smoked the loft out). Since then, the estates manager has instructed yearly cleaning to be done, and MWC issued for each fan cleaned!

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As I said earlier in this thread Lec I couldn't believe the state of a small kitchen fan I came across recently, so much heat had been developed that the plastic housing was almost unrecognisable, just lucky that the windings went o/c before the flames started! I think it's made me take the 3 amp fuse a little more seriously now. This one had been wired into the back of a ring socket btw.

totally un related, but on my motorbike the alarm has a 1A fuse, anyhow the other day it started playing up, so I cut the imobolisor wires out of the loom so the bike would run, this still left the alarm working as a siren and flashing LED.
Yesterday I had a look at it to see what went wrong, upon removing it from the bike I could smell it had burning on it, I opened it up, only screwed together, well inside I was shocked to find melted plastic, wires welded together causing a short, but a fuse that still hadn't blown??? 12 volts 1 amp buts lots of damage, needless to say it's all in the bin now.